1. Field of the Invention
The present disclosure relates to a battery pack provided in a vehicle.
2. Description of Related Art
A hybrid vehicle, an electric vehicle, and the like is provided with a battery pack as a battery for driving a rotary electric machine and for accumulating electric power generated by the rotary electric machine or electric power charged from external power. It is known to configure a battery pack such that two or more cell stacks are placed in one battery outer case. Further, each of the cell stacks may be configured such that battery cells and resin frames provided with a refrigerant passage are laminated alternately and then restricted by a restraint member. A configuration of such a battery pack is disclosed in Japanese Patent Application Publication No. 2014-135237 (JP 2014-135237 A), for example.
Here, each of the battery cells generates heat along with charging and discharging. Excessive heat generation can cause the temperatures of the battery cells to increase, which may decrease the performance and life of the battery cells. In view of this, it has been proposed that each battery cell is cooled down by using, as refrigerant, air taken in from outside a battery pack. For example, resin frames in a cell stack are each provided with a passage for guiding the refrigerant between the battery cells. The refrigerant guided between the battery cells is discharged outside the cell stack after heat exchange is performed between the refrigerant and the battery cells. Accordingly, each of the cell stacks includes an intake port and an exhaust port for the refrigerant.
Two or more cell stacks may be accommodated in a battery outer case for a battery pack. In this case, respective exhaust ports of adjacent cell stacks face each other, so that exhaust gases therefrom might interfere with each other. The heated exhaust gases, that is, hot blasts interfere with each other, so that the hot blasts remain around the cell stacks for a long time. As a result, the cell stack receives thermal influence from its adjacent cell stack, which may cause a decrease in cooling efficiency, and eventually, a decrease in durability and performance. One conceivable solution would be to increase the distance between adjacent cell stacks. However, increasing the distance between adjacent cell stacks might increase the size of the battery pack.